Sterically Hindered Amine Catalysts for Stable Polyurethane Foams
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Solution Overview
Problem
The shelf-life of polyol premix compositions containing certain hydrohaloolefins like HFO-1234ze and HFCO-1233zd is compromised due to the reaction with amine catalysts, leading to decomposition of the blowing agent and alteration of polymeric silicone surfactants, resulting in poor foam structure and collapse during foam formation.
Innovation Solution
Incorporating sterically hindered amines such as dimorpholinodiethylether, N-ethyl ethylmorpholine, and N-methylimidazole into the polyol premix composition to reduce reactivity with hydrohaloolefins, ensuring stable foam production even with aged polyol blends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional amine catalysts are used in polyol premix compositions containing hydrohaloolefins, then the foam formation process is catalyzed, but the blowing agent decomposes and surfactants are altered during storage, leading to poor foam structure and collapse
Solution Approach 1:
The patent changes the chemical structure parameter of the amine catalyst by introducing steric hindrance through substituted morpholine and imidazole rings. This structural modification reduces the reactivity of the catalyst with hydrohaloolefins while maintaining its foam-forming catalytic activity, thereby preventing decomposition during storage while preserving foam formation capability
Solution Approach 2:
The patent replaces conventional amine catalysts that cause decomposition with sterically hindered amine catalysts that remain stable during storage. Although the hindered catalysts may have slightly reduced initial reactivity, they provide reliable long-term stability, effectively treating the catalyst selection as a critical quality parameter rather than a cost optimization
2Duration of action of stationary object
If the polyol premix composition is stored for extended periods, then shelf-life is achieved, but the amine catalyst reacts with hydrohaloolefins causing decomposition and foam collapse
Solution Approach 1:
The patent applies preliminary anti-action by selecting sterically hindered amine catalysts that are pre-designed to resist unwanted side reactions with hydrohaloolefins. The steric hindrance creates a protective effect that prevents the catalyst from attacking the blowing agent during storage, thereby maintaining composition integrity throughout the shelf-life period
Solution Approach 2:
The sterically hindered amine catalyst acts as an intermediary that mediates between the need for catalytic activity and the need for storage stability. The bulky substituents on the catalyst molecules create a steric barrier that prevents direct interaction with hydrohaloolefins, while still allowing the catalyst to perform its intended function during foam formation
3Speed
If non-sterically hindered amine catalysts are used, then rapid foam formation is achieved, but the blowing agent decomposes and cell structure becomes irregular during storage
Solution Approach 1:
The patent modifies the kinetic parameters of the catalyst by introducing steric hindrance, which reduces the rate of unwanted side reactions with hydrohaloolefins during storage while maintaining adequate catalytic activity for foam formation. This parameter adjustment balances speed and precision requirements
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The use of sterically hindered amines maintains the integrity of the blowing agent and surfactants, allowing for the production of high-quality foams with uniform cell structure and preventing collapse, even after prolonged storage.
Implementation Method 1
Incorporating sterically hindered amines such as dimorpholinodiethylether, N-ethyl ethylmorpholine, and N-methylimidazole into the polyol premix composition to reduce reactivity with hydrohaloolefins
Implementation Method 2
Heat generated when the polyisocyanate reacts with the polyol volatilizes the blowing agent contained in the liquid mixture, thereby forming bubbles therein
Implementation Method 3
Heat generated when the polyisocyanate reacts with the polyol volatilizes the blowing agent contained in the liquid mixture
Implementation Method 4
a polyol premix composition which comprises a combination of a blowing agent, which is preferably a hydrohaloolefin, a polyol, a silicone surfactant, and an amine catalyst
Data Source
AI summary
The invention provides polyurethane and polyisocyanurate foams and methods for the preparation thereof. More particularly, the invention relates to open-celled, polyurethane and polyisocyanurate foams and methods for their preparation. The foams are characterized by a fine uniform cell structure and little or no foam collapse. The foams are produced with a polyol premix composition which comprises a combination of a hydrohaloolefin blowing agent, a polyol, a silicone surfactant, and a sterically hindered amine catalyst.